class.c

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/*
 * RTC subsystem, base class
 *
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <[email protected]>
 *
 * class skeleton from drivers/hwmon/hwmon.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/kdev_t.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

#include "rtc-core.h"


static DEFINE_IDA(rtc_ida);
struct class *rtc_class;

static void rtc_device_release(struct device *dev)
{
    struct rtc_device *rtc = to_rtc_device(dev);
    ida_simple_remove(&rtc_ida, rtc->id);
    kfree(rtc);
}

#ifdef CONFIG_RTC_HCTOSYS_DEVICE
/* Result of the last RTC to system clock attempt. */
int rtc_hctosys_ret = -ENODEV;
#endif

#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
/*
 * On suspend(), measure the delta between one RTC and the
 * system's wall clock; restore it on resume().
 */

static struct timespec old_rtc, old_system, old_delta;


static int rtc_suspend(struct device *dev, pm_message_t mesg)
{
    struct rtc_device   *rtc = to_rtc_device(dev);
    struct rtc_time     tm;
    struct timespec     delta, delta_delta;
    if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
        return 0;

    /* snapshot the current RTC and system time at suspend*/
    rtc_read_time(rtc, &tm);
    getnstimeofday(&old_system);
    rtc_tm_to_time(&tm, &old_rtc.tv_sec);


    /*
     * To avoid drift caused by repeated suspend/resumes,
     * which each can add ~1 second drift error,
     * try to compensate so the difference in system time
     * and rtc time stays close to constant.
     */
    delta = timespec_sub(old_system, old_rtc);
    delta_delta = timespec_sub(delta, old_delta);
    if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
        /*
         * if delta_delta is too large, assume time correction
         * has occured and set old_delta to the current delta.
         */
        old_delta = delta;
    } else {
        /* Otherwise try to adjust old_system to compensate */
        old_system = timespec_sub(old_system, delta_delta);
    }

    return 0;
}

static int rtc_resume(struct device *dev)
{
    struct rtc_device   *rtc = to_rtc_device(dev);
    struct rtc_time     tm;
    struct timespec     new_system, new_rtc;
    struct timespec     sleep_time;

    rtc_hctosys_ret = -ENODEV;
    if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
        return 0;

    /* snapshot the current rtc and system time at resume */
    getnstimeofday(&new_system);
    rtc_read_time(rtc, &tm);
    if (rtc_valid_tm(&tm) != 0) {
        pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
        return 0;
    }
    rtc_tm_to_time(&tm, &new_rtc.tv_sec);
    new_rtc.tv_nsec = 0;

    if (new_rtc.tv_sec < old_rtc.tv_sec) {
        pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
        return 0;
    }

    /* calculate the RTC time delta (sleep time)*/
    sleep_time = timespec_sub(new_rtc, old_rtc);

    /*
     * Since these RTC suspend/resume handlers are not called
     * at the very end of suspend or the start of resume,
     * some run-time may pass on either sides of the sleep time
     * so subtract kernel run-time between rtc_suspend to rtc_resume
     * to keep things accurate.
     */
    sleep_time = timespec_sub(sleep_time,
            timespec_sub(new_system, old_system));

    if (sleep_time.tv_sec >= 0)
        timekeeping_inject_sleeptime(&sleep_time);
    rtc_hctosys_ret = 0;
    return 0;
}

#else
#define rtc_suspend NULL
#define rtc_resume  NULL
#endif


struct rtc_device *rtc_device_register(const char *name, struct device *dev,
                    const struct rtc_class_ops *ops,
                    struct module *owner)
{
    struct rtc_device *rtc;
    struct rtc_wkalrm alrm;
    int id, err;

    id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
    if (id < 0) {
        err = id;
        goto exit;
    }

    rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
    if (rtc == NULL) {
        err = -ENOMEM;
        goto exit_ida;
    }

    rtc->id = id;
    rtc->ops = ops;
    rtc->owner = owner;
    rtc->irq_freq = 1;
    rtc->max_user_freq = 64;
    rtc->dev.parent = dev;
    rtc->dev.class = rtc_class;
    rtc->dev.release = rtc_device_release;

    mutex_init(&rtc->ops_lock);
    spin_lock_init(&rtc->irq_lock);
    spin_lock_init(&rtc->irq_task_lock);
    init_waitqueue_head(&rtc->irq_queue);

    /* Init timerqueue */
    timerqueue_init_head(&rtc->timerqueue);
    INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
    /* Init aie timer */
    rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
    /* Init uie timer */
    rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
    /* Init pie timer */
    hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    rtc->pie_timer.function = rtc_pie_update_irq;
    rtc->pie_enabled = 0;

    /* Check to see if there is an ALARM already set in hw */
    err = __rtc_read_alarm(rtc, &alrm);

    if (!err && !rtc_valid_tm(&alrm.time))
        rtc_initialize_alarm(rtc, &alrm);

    strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
    dev_set_name(&rtc->dev, "rtc%d", id);

    rtc_dev_prepare(rtc);

    err = device_register(&rtc->dev);
    if (err) {
        put_device(&rtc->dev);
        goto exit_kfree;
    }

    rtc_dev_add_device(rtc);
    rtc_sysfs_add_device(rtc);
    rtc_proc_add_device(rtc);

    dev_info(dev, "rtc core: registered %s as %s\n",
            rtc->name, dev_name(&rtc->dev));

    return rtc;

exit_kfree:
    kfree(rtc);

exit_ida:
    ida_simple_remove(&rtc_ida, id);

exit:
    dev_err(dev, "rtc core: unable to register %s, err = %d\n",
            name, err);
    return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(rtc_device_register);


void rtc_device_unregister(struct rtc_device *rtc)
{
    if (get_device(&rtc->dev) != NULL) {
        mutex_lock(&rtc->ops_lock);
        /* remove innards of this RTC, then disable it, before
         * letting any rtc_class_open() users access it again
         */
        rtc_sysfs_del_device(rtc);
        rtc_dev_del_device(rtc);
        rtc_proc_del_device(rtc);
        device_unregister(&rtc->dev);
        rtc->ops = NULL;
        ida_simple_remove(&rtc_ida, rtc->id);
        mutex_unlock(&rtc->ops_lock);
        put_device(&rtc->dev);
    }
}
EXPORT_SYMBOL_GPL(rtc_device_unregister);

static int __init rtc_init(void)
{
    rtc_class = class_create(THIS_MODULE, "rtc");
    if (IS_ERR(rtc_class)) {
        printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
        return PTR_ERR(rtc_class);
    }
    rtc_class->suspend = rtc_suspend;
    rtc_class->resume = rtc_resume;
    rtc_dev_init();
    rtc_sysfs_init(rtc_class);
    return 0;
}

static void __exit rtc_exit(void)
{
    rtc_dev_exit();
    class_destroy(rtc_class);
    ida_destroy(&rtc_ida);
}

subsys_initcall(rtc_init);
module_exit(rtc_exit);

MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
MODULE_DESCRIPTION("RTC class support");
MODULE_LICENSE("GPL");